[countable]

1. a message that is written down or printed on paper and usually put in an envelope and sent to sb
   信；函◆a letter of complaint
   投诉信◆Who is the letter addressed to?
   这封信寄给谁？◆You will be notified by letter.
   将用信函通知你。◆guidelines for writing effective sales letters (= to possible customers)
   撰写有效销售信函指南⨁to mail / post / send a letter
   寄信 ⨁ to draft / write a letter
   起草一封信；写信 ⨁ to get / open / receive a letter
   收到／打开／接到信 ⨁ to acknowledge / answer / reply to a letter
   来函收悉；回信 ⨁ a business / personal / formal / informal letter
   商务／个人／正式／非正式信函

●the ˌletter of the ˈlawthe exact words of a law or rule rather than its general meaning
法律（或法规）的准确字面意义◆Although the company sticks to the letter of the law, its employment practices are clearly unfair.
尽管这家公司严守法律的字面意义，但实际执行雇用条例时显然是不公平的。